There is a constant ever pressing need for further simplification of devices which currently exist. The principal reason for simplification relates to economics since it is deemed desirable to design an article which will function efficiently to perform a given function but is less expensive in terms of manufacture and therefore in the ultimate cost to the consumer. A further reason for desiring simplification is the fact that the consuming public has turned more to a self help approach toward many job functions, and in the interest of facilitating the consumers desire to perform many job functions on a do-it-yourself basis, simplification of tools, equipment and the like is desirable.
In the area of electrical equipment, one of the most widely used items relates to a connector which functions for interconnecting conduit to an electrical junction box. It will be well understood that in virtually every electrical installation, a plurality of electrical junction boxes are installed for switches, outlets, lights, and the like, and conduit is strung in a manner to interconnect such boxes. It will therefore be appreciated that the electrical connectors utilized to interconnect the conduit to the boxes are probably the most widely used piece of electrical equipment. However, it will be noted that in most instances, electrical connectors are designed and constructed of at least two pieces in order to effect the interconnection. As is commonly known, the connector includes a first piece which has a head portion and a threaded portion, the threaded portion being inserted through the knockout plug in the electrical box, and a thread gripping head which includes a compression ring, which is slid over the conduit until the conduit is inserted into the tubular portion of the threaded and emanating from the electrical box. Once the conduit is in place, the thread gripping portion including the compression ring is screw-threadedly mounted on the threaded end of the connector emanating from the box. By tightening down on the thread gripping head, the compression ring is forced into biting engagement with the conduit.
In the above description, it is quite apparent that the installation of a connector is cumbersome and does require multiple steps incident to the installation. In addition, it has been known that compression rings will often become disengaged from the thread gripping head and in such eventuality, the thread gripping portion of the connector becomes useless.
In another version of an electrical connector, especially useful for flexible conduit, the connector is basically a multi-piece unit which includes a threaded portion intended to be inserted externally through the knockout portion and held in position by a thread gripping nut internally of the electrical box, the flexible conduit gripping means consisting of a bridge from which a grip bar is suspended by two screws. Once the conduit is inserted between the bridge and the grip bar, the screws are tightened thereby to restrain the conduit in position. Once again, an electrical connector of this type is formed by multiple pieces, and therefor requires a multi-step procedure to install. In addition, should any of the pieces become lost, for example, either or both of the screws intended to tighten the grip bar down against the bridge, the connector becomes useless and must be discarded.
In terms of the patented art, various attempts have been made to simplify an electrical connector from both the economic standpoint, as well as the standpoint of the installation. The ultimate goal is to achieve a one-piece electrical connector which is of ultimate simplicity in terms of the steps of installation.
It will be observed that in U.S. Pat. No. 3,369,071, basically a one-piece electrical connector is illustrated therein. It will be noted that the connector therein includes a head portion intended for insertion through the knockout portion of the electrical box, and a conduit carrying portion or sleeve which extends externally of the box. The head portion is retained internally of the box by means of a pair of tongues which must be pried outwardly away from the head portion such that they are positioned behind the wall of the electrical box. Forward of the head portion is a rib or projection such that the electrical connector is in effect fixably mounted as between the tongues which are extended, and the rib portion which is external thereto. The conduit or cable is fished through the sleeve portion and held in position by a plurality of dimples on the inner surface of the wall, as well as by means of a shoulder which is, in effect, a cut in the wall of the sleeve portion causing a biting corner to bite into the conduit wall.
While the device depicted in U.S. Pat. No. 3,369,071 would appear to simplify the electrical connector art, nevertheless, a device of this type has not achieved any degree of commercial success for the reason that it is believed that it is difficult for the user thereof to manipulate the connector when inserted in the box in order to engage the connector to the box. For example, it will be observed that one must insert a tool of some kind, such as a screwdriver or the like, with a view toward engaging the tongues to bend them outwardly in order to securely affix the connector to the box. This often is difficult, especially where an electrical box is located in a tight area. In addition, a connector of this type which requires that the sleeve body be cut into in order to form a shoulder to grip against the conduit would probably not be accepted by most building codes since it necessarily means that there is an open space in the connector which could permit the passage of a spark in the event of a short. Hence, a connector of this type would likely not be approved by any modern electrical code.
Another version of an approved electrical connector is shown in U.S. Pat. No. 3,801,131 which basically relates to a two piece connector. There is provided a threaded portion which has a head, the threaded portion being inserted from internally of the box and extending outwardly and includes a nut portion which screw-threadedly fastens onto the threaded portion once the conduit is inserted in position. It will further be noted that the nut portion includes a section of deformable material forming a part of the tubular body, while the interior surface of the threaded portion includes a series of annular ridges for gripping the conduit. When the nut portion is screw-threadedly tightened onto the threaded portion, it will be apparent that the tubular body forms around the deformable material causing the annular ribs to bite into the conduit and retain the electrical cable in position. While the device shown in Patent 3,801,131 appears to be a more simplified device since it consists of two pieces, nevertheless, it will be appreciated that the cost of manufacture would be significant since the device must be made with a deformable section embedded in the body of a tubular threaded portion member. Hence, a device of this type has not found wide acceptance commercially as an alternate type of connector for use in the domestic market.
Still another form of a connector intended as a simplified or one-piece structure is shown in U.S. Pat. No. 3,814,467. In this instance, the connector is designed to interconnect flexible conduit such as B-X cable to an electrical box. It will be noted in this instance that the connector is formed with a pair of flared-out ribs such that the inner portion of the connector may be secured to the internal portion of the box, while the external portion includes a lip intended to override one of the contoured ribs of the flexible conduit. It will be appreciated, however, that once again due to the precise construction of the connector shown in U.S. Pat. No. 3,814,467, the cost of manufacture is significant since it entails the provision of a number of flared ribs, contoured ribs, and the like. In addition, a connector of this type would not be particularly suitable for a smooth wall type conduit and hence, could only find application in connection with the flexible type B-X cable.
Various other types of connectors are shown in other patents. For example, U.S. Pat. No. 3,701,505 shows still another version of a connector which includes the structure of a bridge and gripping bar which may be tightened by screw-threadedly fastening the screws. This type of connector is well known in the art. As indicated previously, however, the connector shown therein necessarily requires construction from a plurality of parts, which necessarily increases the cost of construction and requires more manipulative steps in order to install.
In most other instances, the connectors intended for use on electrical boxes require, at the very least, two parts. The first general part is generally inserted from the inside of the electrical box or junction box and extends outwardly such that a threaded portion is exposed externally of the box, and a threaded nut portion is utilized for fastening down onto the threaded portion. This, for example, is typical of the construction shown in U.S. Pat. No. 3,600,008.
It is believed that a more simplified version of a connector which is essentially one-piece in construction, and eliminates costly manufacturing steps is desirable, and would find a broad level of acceptance. The present invention seeks to provide such a one-piece electrical connector.